Some investors may wish for so-called "set it and forget it" stocks. However, considering the risks and inherent volatility that can come with holding stocks in companies, such thinking is not advisable with individual stocks.

Nonetheless, prospective stockholders will sometimes encounter companies poised to deliver gains over a lifetime. Due to their growing customer bases and prospects for further expansion, Innovative Industrial Properties (IIP) (IIPR -0.64%) and T-Mobile (TMUS -0.30%) hold the potential for this level of long-term growth.

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1. Innovative Industrial Properties

IIP is the only real estate investment trust (REIT) to specialize exclusively in properties for the cultivation of medical-use cannabis. Currently, it owns 55 properties across the country for this purpose. Since most U.S. states allow some form of legal cannabis, IIP serves only a tiny portion of its addressable market.

Moreover, since cannabis companies generally lack access to the banking system because of federal prohibitions against marijuana sales, IIP plays a unique role in the industry. To provide these companies with financing, IIP will buy their land and lease the property back to the former owner. This has not only led IIP to new property acquisitions; it also has helped keep its properties 100% leased.

Through this approach, the company generated almost $146 million in revenue in the first nine months of 2021, 82% more than in the first nine months of 2020. This resulted in net income for the first three quarters of 2021 of $85 million, a 94% increase over the same period in 2020. Limiting the growth in operating expenses to 42% helped boost earnings, even though interest costs more than doubled during that time and interest income fell by more than 90%.

This success helped the stock rise by approximately 50% over the last year. Furthermore, as a REIT, it must pay out at least 90% of its net income in dividends to shareholders. Rising profits have led to a dividend increase in each of the last six quarters. With the dividend now at $6 per share annually, shareholders receive a yield of 2.5%. This is much better than the average S&P 500 dividend yield of about 1.3%. Additionally, with the stock trading at around $240 per share as of the time of this writing, it should allow for decent share purchases within a $2,500 budget.

2. T-Mobile

T-Mobile is one of only three companies providing 5G data service in the U.S., and the impact of T-Mobile's 5G lead is just starting to be seen. Consequently, it continues to outpace its rivals AT&T (T -2.00%) and Verizon (VZ -1.11%) on net account additions, reporting 1.3 million in Q3 alone.

Moreover, T-Mobile has made an effort to compete on service quality with its rivals. Its purchase of Sprint increased its portfolio of wireless spectrum. Also, in March, T-Mobile invested just over $9 billion in acquiring C-band spectrum. The spectrum amounts to "RF real estate," which will allow the company to improve its service in specific markets.

To this end, T-Mobile plans to spend between $12.1 billion and $12.3 billion this year to upgrade its network. It also competes in customer service, winning the No. 1 ranking from J.D. Power for customer care.

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Such accolades likely contributed to its $59 billion in revenue during the first three quarters of 2021, 23% more than in the same period last year. As a result, T-Mobile earned $2.6 billion in the first nine months of the year. That figure climbed 13% from the year-ago period. With equipment costs surging by 48%, the profit increase lagged the revenue growth rate.

Admittedly, its P/E ratio of 43 far exceeds that of Verizon. However, T-Mobile stock has more than doubled over the last five years. In comparison, the stocks of AT&T and Verizon lost value over that time. At just under $120 per share, T-Mobile is the clear growth name in this space and offers shares at an affordable price for smaller investors.