If you are a student or working on a personal portfolio, use the free alternatives. They are high-quality and will not get you sued. If a client is paying you, bill them for the $49 font license. A $49 font license is cheaper than a $5,000 legal bill.
Aktiv Grotesk was designed as a modern, "flexible powerhouse" to rival classic grotesque typefaces like Helvetica and Univers. Aktiv Grotesk Extended Font Free Download-