On February 7, LastPass announced that LastPass Premium will now cost $36 per year ($3 per month)[1], up from $24 per year.
In a separate blog posted on February 12, LastPass noted that their app grew by 132% last year[2].
Previously, the yearly premium was at $12. It then doubled to $24 after August, 2017[3][4].
Sources:
[1] LastPass blog: A Change to LastPass Premium. Posted on Feb. 7, 2019.
[2] LastPass blog: Security-Based Apps are Skyrocketing in Popularity – But Why?. Posted on Feb. 12, 2019.
[3] LastPass blog: Updates to the LastPass personal lineup. Posted on August 3, 2017.
[4] The Verge: LastPass doubles premium tier prices to $24 a year, and some users aren't thrilled. Posted on Aug 3, 2017.
Personal take: I bought a 5-year subscription some years ago when it was at $1 per month. Now it has tripled to $3. When the sub expires, I hope it doesn't cost $5/month.